Efficacy and Safety of Atezolizumab in Chinese Patients With Advanced Thymic Carcinoma: A Multicenter, Single-Arm Phase 2 Study

Abstract

Introduction

There are limited treatment options for thymic carcinoma. This study aimed to evaluate the efficacy and safety of atezolizumab for the treatment of advanced thymic carcinoma after failure with prior systemic therapy.

Patients and Methods

Patients aged ≥ 18 years with advanced thymic carcinoma after failure with prior systemic therapy were enrolled at 10 medical centers in China. Atezolizumab 1200 mg was administered on Day 1 (baseline) every 3 weeks until unacceptable toxicity/loss of clinical benefit. The primary efficacy endpoint was the confirmed objective response rate in the full analysis set.

Results

Between 29 July 2020 and 28 December 2022, 34 patients enrolled (median age, 54.5 years), and 16 (47.1%) had received ≥ 2 prior lines of therapy. At the cut-off date (July 16, 2023), the median follow-up duration was 19.1 months. The confirmed objective response rate (ORR) was 14.7% (95% confidence interval, 5.0%-31.1%); disease control rate, 58.8%; median progression-free survival (PFS), 3.2 months; 24-month OS rate, 63.2%; Better ORR and PFS were observed in PD-L1-positive patients versus PD-L1-negative patients (40.0% vs. 0% and 7.4 vs. 1.5 months, respectively). No correlation was observed with TMB. The incidence of adverse events (AEs) was 94.1%; serious AEs, 26.5%; immune-related AEs, 29.4%; and AEs leading to drug withdrawal, 2.9%.

Conclusions

In patients with advanced thymic carcinoma who had failed prior systemic therapy, atezolizumab was well-tolerated with a manageable toxicity profile and showed encouraging the antitumor activity, especially in patients with PD-L1-positive tumors.